Qian Chen, Sung Chul Bae, and Steve Granick Journal of the American Chemical Society Article ASAP
This paper outlines a method for creating complex three dimensional self-assembled architectures from monodisperse colloids. The authors coat polystyrene beads with titanium and gold and then etch away the middle layer using a monolayer deposition technique to reveal the hydrophobic patch. The first asymmetrical charged patches are "activated" by placing the colloids in an ionic solution causing primary structures to form. The second charged patch is then activated by increasing the ionic strength of the solution leading to the formation of more complex secondary structures.